I do think that what's been offered so far sums it up.
When I first started working in the 1980s as a tech geek at a defense contractor (first job) it was expected that one would always show up in dress pants, shirt, and tie at a minimum. I think this was largely because there were frequent visits from various military brass who were in full uniform and the company wanted to give an equally formal impression, but in street clothes, and everyone knows that a private and a general do not wear exactly the same uniform.
Over the years dress codes, both formal written and unwritten ones, have definitely relaxed, and I say all for the better. I love the way I look, and many other people look, in formal attire (be it tuxedo for social occasions or suit and tie, or the equivalent in women's wear in context) but the amount of both time and money necessary to maintain a full wardrobe of business attire on a daily basis is ridiculous, at least if you want to look genuinely good [everything pressed] rather than grabbing "wash and wear" [which isn't] and throwing it on.
Most positions do not require formal dress and many are hindered by it. I never loved crawling under desks to deal with wiring and the like in good dress clothing while doing so in good jeans (as opposed to the variety that become yard work clothing) and a polo shirt doesn't bother me at all.
Also, whether people like to admit it or not in this day and age, clothing is very powerful in telegraphing status and power. When someone has dressed in "status and power" mode that tends to put people who are not dressed similarly in a psychologically uncomfortable position. I prefer that, say, my doctor does not dress in full suit and tie with accessories to match, as it makes him less approachable and easy to talk to, whether intended or not. People subconsciously respond to all sorts of cues regarding power dynamics and there are lots of work/business situations where that response does not truly benefit either side of the equation.
Since I've been self-employed as a one-man technical support "team" I have worn virtually nothing but jeans and polo shirts to visit clients. I feel at ease in this clothing and the clients, even if they're a bit more formally dressed, seem to feel at ease with that, too.
I can also say that I never did get why "the office" has been given so much (undue, in my opinion) respect and required significantly more formality. Dress has zero to do with expertise, and when I engage someone's services it's because I already know they meet the training, licensure, whatever requirements to do the job. While I don't want someone who is being intentionally provocative in their style (and I don't mean sexually provocative, or at least not specifically sexually provocative) I give a very wide latitude in the "normal dress" bell curve.
I do think, though, that depending on the business you want to go into, or for which you wish to be contracted by, you must consider what the standards are today in that milieu. I could not get away with my chosen style of dress if I wanted to be in high-dollar banking, the fashion industry, or any number of other areas where clothing as a social marker is still central.